97 



TAB. CCCL1II. 



Common Argillaceous Slate, or Schist us* 



Class 2. Earths. Order 2. Aggregate. 

 Syn. Schistus. Linn. Syst. ed. 13. 3. 37. 

 Argillite. Kirw. 354. 

 Argile schisteuse. Haiiy, 4. 446. 

 Clay Slate. Jameson's Mineral. 1. 334. 



1 he Slate commonly known as of a slate-grey colour is 

 found in many places in Great Britain, from Penzance in 

 Cornwall, through Wales and Westmoreland to the Calton 

 Hill in Scotland, where there are primitive rocks. Between 

 the different beds of Slate which lie in that direction are 

 beds of Lime-slate, as at Plymouth-Dock, where one side 

 is Slate and the other Limestone. Many parts of Scot- 

 land, and Wicklow in Ireland, abound with this substance, 

 and some afford much variety. Lord Penryn's, at Nan- 

 francon near Bangor, is quarried in large quantities for 

 London ; the dark grey and lighter sorts are used for slating 

 houses, and the less fissile ones serve for posts, or turning 

 into candlesticks and fanciful ornaments. Coal buttons 

 have been made, of Slate, which proved very durable, and 

 often suited well with a dark, or light brown, or gray, or 

 mottled coat. 



The f'r or t figure shows the durable Slate of Cornwall, 

 which is used in as thin and light plates as any. It has a 

 close, glossy, and nearly even appearance, and consists 

 chiefly of Chlorite with an intimate mixture of OuartZj 



VOL. IV. j 



